1904.] NATURAL SCIENCES OF PHILADELPHIA. 607 



Aster linariifolius L., Quercus ilicifolia, Gaylussacia resinosa |Tott and 

 Gray, G. frondosa Torrey and Gray, Vaccinium vacillans Sol., Epigcea 

 repens L., Gaultheria procumbens L., Cassandra calyculata Don and 

 Rhododendron viscosum Torrey. Another peculiarity is the substitu- 

 tion of Pinus rigida ^lill on the mountains for the Piniis slrobus L. 

 of the surrounding country. 



The ridges of the Green Pond system, known at Greenwood Lake as 

 Bearfort and Bellvale mountains, and in New York as the Skimne- 

 munk, have a somewhat similar summit flora, consisting of Quercus 

 ilicifolia Wang., Solidago puberula Nutt., Tephrosia virginiana Pers., 

 Lespedeza hirta Ell., Arctostaphylos uva-ursi Spreng, Aster linariifolius 

 L., various huckleberries, blueberries and other sand plants. 



The reason for the somewhat remarkable similarity of the pine 

 barren and summit mountain floras is usually attributed to the simi- 

 larity of the soil on the mountains to that of the plains bordering the 

 coast. It is probably true that the plants occupy these areas because 

 they have adapted themselves to growing in soils of silicious sands, 

 but to say that the soil is the prime factor in their distribution is put- 

 ting the case too strongly. The writer believes, from an investigation 

 that he has made of the problems involved, that the flora of the moun- 

 taiixs is peculiarly an endemic one, showing relict endemism, and that 

 the flora of the pine barren is a derived one, and is an illustration of 

 Drude's principle enunciated above. The crest of the Kittatinny Moun- 

 tains represents the level of a plain that existed prior to the great period 

 of erosion which carved out the mountain ranges and has been several 

 times elevated and depressed. During the period of its more extensive 

 plain character, the plants above mentioned were distributed over 

 the area now represented by the crests of the Shawangunk Moun- 

 tains in New Jersey and the Skunnemunk Mountains in New 

 York. With the wearing away of the plain this more ancient flora 

 remained in a relict form on the summits of the mountains mentioned. 

 This antedated many years the upheaval of the New Jersey coast plain, 

 which was, after its appearance above the surface of the sea. an open 

 field for the migration of plants from nearby formations. The pioneers 

 into the elevated coastal plain were those species nearest at hand and 

 most mobile and, by reason of occupancy of a similar soil, well adapted 

 to meet the new conditions of environment. If we apply these princi- 

 ples to the prolslem in hand, we naturally reach the conclusion that 

 certain plants of the coastal flora are derived from the formations near- 

 est at hand which present similar environmental conditioas, and are, 

 therefore, for the coastal region comparatively new, so that the summit 



